Polymeric shells, including unsupported medical, surgical and other gloves, are typically made of latex. These polymeric shells are produced in an assembly line fashion by dipping a coagulant-coated former of desired shape into an aqueous latex emulsion, thereby coagulating the latex. The coagulated layer is subsequently cured to form the polymeric shell. The aqueous latex emulsion may comprise additives, including viscosity modifiers, waxes, surfactants, stabilizers, cross-linking agents and the like, to produce a cured latex product having specific characteristics, such as thickness, tensile strength, tear and penetration resistance, flexibility; etc., in a controlled manner. Aqueous latexes of different compositions are known in the art, and they include natural rubber latexes, synthetic polyisoprenes, and other synthetic latexes, including neoprene, nitrile compositions, and the like. Examples of polymeric shells made from a typical aqueous dipping process are described in U.S. Pat. No. 3,268,647 to Hayes et al., which discloses the manufacture of rubber gloves. Nitrile latex gloves are commonly used to provide chemical resistance.
Supported polymeric shells with a liner are known in the art and are commonly used in industrial environments, such as in the form of gloves for protecting hands, where use of a strong latex product is needed. A number of patents disclose coating the liner with a latex composition. For example, U.S. Pat. No. 2,083,684 to Burke discloses rubber-coated gloves and a method of making the same. U.S. Pat. Nos. 4,514,460; 4,515,851; 4,555,813; and 4,589,940 to Johnson disclose slip-resistant gloves and a method for their manufacture. U.S. Pat. No. 5,581,812 to Krocheski discloses a leak-proof textile glove. The inner surface of a cut-resistant textile layer is bonded to a leak-proof, petroleum-resistant, polymeric material, such as PVC, without an intervening adhesive layer, since the leak-proof polymeric material is applied to a liner placed on a former. U.S. Pat. No. 5,822,791 to Baris discloses a protective material and a method wherein a cut-resistant, protective layer is coated with an impervious elastomeric material.
A typical process for producing these supported gloves includes the use of a liner, which is dressed over a former, optionally treated with a coagulant, and dipped into an aqueous latex emulsion to form a gelled latex layer over the liner, which is then cured. The penetration of the aqueous latex emulsion into the dressed liner results in “strike-through,” or “penetration,” which creates an unsightly appearance of the supported product, discomfort on the bare hand, and makes the article more rigid and less flexible. A number of steps are taken to minimize “strike-through,” including coagulant coating of the liner as a blocking agent, and increasing the viscosity of the aqueous latex emulsion to prevent the penetration of the aqueous emulsion into the liner. The aqueous latex emulsion used may comprise several additives, such as stabilizers, foaming agents, cross-linking agents, waxes, and surfactants. The latex composition may be natural rubber, polyisoprene, polychloroprene, nitrile rubber, and the like. These supported polymeric shell products provide sufficient protection to the hands of the wearer. The dipping and drying of a glove former in a latex emulsion to form a glove is disclosed. However, the chemical resistance of the polymeric shell is generally inadequate due to poor coverage of the latex emulsion over the liner and may have holes in the latex layer where the fibers of the liner cross. A further and perhaps more serious consequence of coating over a knitted fabric is the possibility that the resultant polymeric film is compromised, resulting in a non-uniform thickness, which may compromise the chemical-resistant barrier of the film in parts or which may not be liquid-proof. This is due to the potential of surface fibers passing into or through the coating, hence providing an easier path for liquids to pass or permeate through the polymeric film. Foamed latex layers may have interconnected porosity, which also may provide decreased chemical resistance to the supported polymeric shell latex article.
U.S. Pat. No. 4,283,244 to Hashmi discloses a method of making fabric-lined articles. This method of making a lined elastomeric article comprises the steps of applying a coating of adhesive in a liquid state to an elastomeric article on a form, drying the adhesive on the article to form a pressure-sensitive adhesive coating, treating the adhesive coating with a lubricant, and thereafter applying a preformed lining over the article and the adhesive coating to connect adhesively the lining to the elastomeric article. The elastomeric article is a latex product produced by dipping a coagulant-treated former into an aqueous latex emulsion and drying and curing the elastomeric article on the former. The adhesive is 68096-01 resin supplied by Evans Adhesives of Columbus, Ohio, suspended in water. The elastomeric article on the former is dipped in the adhesive, dried to form a pressure-sensitive adhesive coating, lubricated, and dressed with a liner. The lined elastomeric article is removed from the former and turned inside-out. Unfortunately, sweating combined with body temperature results in the extraction or dissolution of the adhesive, producing an unpleasant skin feel. The adhesive also is soft, has low strength properties, and stays tacky even after drying.
U.S. Pat. No. 4,847,918 to Sturm discloses a protective hand covering and method of manufacture. This flexible fire-retardant and heat insulating fabric inner glove is mounted within and cemented to a flexible, watertight, vapor-permeable plastic glove using adhesive cement applied to the fabric liner and the plastic glove. Flexible tear resistant reinforcement is secured at the fingertips of the fabric inner glove and the plastic glove using a hot melt adhesive. The reinforcement is not indicated to be cut resistant and is not completely secured to an elastomeric material.
U.S. Pat. No. 5,070,540 to Bettcher et al. discloses a protective garment having a cover, a fabric liner, and a coating of elastomeric material permeating the cover and adhering the liner and cover together. The fabric liner is in a skin-contacting region. The cover is cut resistant with wire strands. The cover can be knit from yarn that has a core having 2 to 6 strands of stainless steel wire and a parallel synthetic polymer fiber strand, and the core can be wrapped with strands of non-aramid fiber in opposite directions one on top of the other. The elastomeric material can be formed from nitrile latex, which is said to infiltrate the cut resistant cover, but does not infiltrate through the fabric liner, yet infiltrates sufficiently to adhere the liner to the cover. Such precision of latex dipping, however, is not readily realized in industrial practice.
U.S. Pat. No. 5,822,795 to Gold discloses multi-layer glove constructions and methods of constructing multi-layer gloves. This multi-layer glove incorporates an inner liner, intermediate waterproof, windproof and/or breathable membrane layer and an outer shell. The membrane layer is secured to the inner layer and the outer layer by adhesive tapes to provide secure fit between the layers and inhibits the reversibility of layers when the hand is removed from the glove. The crotch region is also inhibited from movement by the membrane layer during use. The multi-layered glove is also assembled more efficiently with improved construction techniques relating to the use of the adhesive strips secured to the outside of the inner liner layer. The multi-layer glove does not have a cut resistant liner and is not indicated to provide chemical resistance and protection.
U.S. Pat. Nos. 6,543,059 and 6,596,345 to Szczesuil et al. disclose a protective glove and a method for making same. This protective glove for a human hand includes an inner glove of polyester, non-woven, needle-punched material and a melt-sprayed polyurethane coating. This non-woven needle-punched material has no mechanical integrity, unlike a woven or knitted fabric and the hot melt-sprayed polyurethane adhesive holds the configuration together forming a glove. The melt-sprayed glove is heated to a temperature of 300 to 325° F. to allow the remelted polyurethane to penetrate the inner glove to a depth short of penetrating to the inner surface of the inner glove. The polyurethane coating on the outer surface of the inner glove cures in approximately 24 hours by reaction with ambient moisture. The inner glove is further coated with a rubberized material to produce an inner glove held together by the rubber, which is then cut to pieces and sewn, to form a glove with internal sewn seams. Such a glove is not liquid-impervious, since these sewn seams are not bonded and leak. Such a glove is liquid-impervious, therefore, not chemically resistant. The protective glove is said to protect from puncture, but the polyester non-woven inner glove will not provide cut resistance.
U.S. Pat. No. 6,539,552 to Yoshida discloses a flexible waterproof glove. This waterproof glove is formed of a flexible inner glove body of a base fabric that is thermally bonded with a low melting thermal plastic resin film and a flexible outer glove body of the same fabric. The thermal bonding of the inner glove with the outer glove is accomplished by heating the glove to melt the low melting thermal plastic resin film, which has a lower melting point than that of the base fabric. The melted thermal plastic resin film results in a watertight glove. The thumb portion of the glove is manufactured separately and bonded to the rest of the glove to provide improved thumb movement. The molten and solidified plastic resin film bonded to both inner and outer glove body results in a watertight glove. The overall rigidity and resistance to movement of the glove is exemplified by the need to attach the thumb component of the glove separately. There is no latex or polymeric shell in this glove. Thus, this glove has no stretch characteristics resembling those that are commonly available in a latex-based glove product.
U.S. Pat. No. 7,007,308 to Howland et al. discloses protective garment and glove construction and method for making same. The garment or glove has a cut and puncture resistant protective liner or multiple liners affixed to the inside shell or outside shell of the garment or glove by means of adhesives or stitching. The cut resistant protective liner may be attached to the outer surface of the inside shell by an adhesive layer. Alternatively, the cut resistant liner may be attached to the inside surface of the outside shell by an adhesive layer. When both inside shell and outside shell are present, the cut resistant liner is only attached to the inside shell by an adhesive layer as shown in FIG. 7. The adhesive is not indicated to be tacky or pressure sensitive. The cut resistant liner is not integrally attached to either the inside shell or the outside shell.
U.S. Pat. Appln. Pub. No. 2006/0068140 to Flather et al. discloses a polymeric shell adherently supported by a liner and a method of manufacture. The liquid-impervious polymeric shell is attached to a liner, which may be cut resistant, by use of a non-tacky thermoplastic adhesive applied by hot melting spraying and melting the adhesive to create a bond between the polymeric shell and the liner. A second polymeric shell may be attached to the liner by the application of non-tacky hot melt adhesive. The adhesive used is non-tacky and is solid at room temperature creating a rigid bond between the liner and the liquid-impervious polymeric shell.
Therefore, there is a need in the art for a latex glove article with a chemically resistant polymeric shell that is soft and flexible that covers the entire hand and wrist while at the same time, the chemically resistant polymeric shell is protected from knife or other sharp object damage. Any damage to the chemically resistant polymeric shell is not easily detected by the user and exposes the user to chemicals that may have severe consequences. The glove needs to be flexible and easy to use in industrial and laboratory environment. There is also a need in the art for a reliable manufacturing process that produces a chemical resistant full coverage glove wherein the chemical resistant polymeric shell is protected by knife or other damage while at the same time providing high level of flexibility. These and other objects and advantages, as well as additional inventive features, will be apparent from the detailed description provided herein.